amounts are insignificant when we consider the amounts used to treat persons for various 
diseases. However, it apparently takes very little penicillin to cause a reaction in 
sensitive persons (6, 11). For instance, Bierlein (6) described a woman who developed 
an anaphylactic reaction when injected intradermally with 0.000003 unit of penicillin. 
This is at least 1,000 times more sensitive than the present microbiological test for this 
antibiotic. It is not too difficult to imagine that such a person would react to very low 
oral doses of penicillin. 
Although penicillin in milk is of primary concern because it is allergenic, other 
antibiotics have been found in the market milk supplies and must also be considered 
adulterants (35, 80). Therefore, all interests may be best served by reviewing the 
literature and presenting information in graphic form on the persistence of the various 
antibiotics and sulfonamides in milk after intramammary, parenteral, and oral admin- 
istration. 
INTERPRETATION OF DATA 
Only the maximal times of persistence and the maximal concentrations of the 
various antibiotics in milk are presented in the graphs. For instance, if an antibiotic 
in an ointment base persisted in the milk of one cow for 1 day and in another cow for 
3 days, the product was recorded as having a 3-day maximal time of persistence. A 
number of factors influence the concentration and persistence of antibiotics in milk. 
Some of these factors, which are necessary for a complete interpretation of the data 
and could not be presented in the graphs, follow: 
(1) The persistence of antibiotics differed in milk from cows in early-, mid- and late 
lactation (33). Whenever this information was given, only the mid-lactation data were 
used. 
(2) The correlation was negative between milk yield and penicillin concentration (50, 
75). Milk production records were not always given; therefore, they were disregarded 
when compiling data for the graphs. 
(3) Foremilk, mid-milk and strippings contain different concentrations of anti- 
biotics (15, 40, 58, 73). Some of the variation in antibiotic concentrations observed by 
various investigators, therefore, might be due to the portion of the milk assayed. 
(4) Some of the investigators tested for antibiotics at lower concentrations thar. 
others; consequently, greater persistence was due, in some instances, to a greater 
sensitivity of the test rather than to any difference in the products. 
(5) The difference in sensitivity of tests for similar antibiotics also exists. For 
instance, the test for Aureomycin is at least four times more sensitive than that for 
Terramycin; thus, some of the greater persistence of Aureomycin may be attributed 
to a more sensitive test. 
Numerous references contained information on antibiotics and sulfonamides in 
milk, but they were not used in the graphs because testing for these compounds was. 
done for limited periods of time or the doses were different from those shown in the 
graphs (4,8,39,42,54,56,64,72,74,77,78). We suggest, therefore, that the original 
references be consulted for complete details about these various factors. 
THE INTRAMAMMARY INFUSION OF ANTIBIOTICS 
Penicillin--Figure 1 shows the range of maximal times for the persistence of 
penicillin in milk after one intramammary infusion of 100,000 units. The data indicate 
that the kind of vehicle in which penicillinis suspended has an influence on its persistence 
in milk, although the various salts of penicillin can also influence the persistency and 
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